Kim Ok-joo, 46, who works at a tollgate on a highway just outside Seoul for more than eight hours nearly every day, can not help but think her drudgery does not really pay off. "It takes only two weeks to use up all my monthly wage," said Kim, a single mother raisingtwo teenage sons. "I often work for 16 hours a days, and even on weekends, by my wasge is never enough to feed m..